As a soilless culturing method for growing plants using mineral nutrient solutions, the hydroponic cultivation technology has been increasingly employed in plant factories to grow plants indoors using artificial lights, such as LED lamps.
In a conventional hydroponic cultivation technology, a cultivation reservoir or a cultivation tank is typically employed in a hydroponic cultivation facility.
In order to ensure an even distribution of the culture solution, a traditional shallow cultivation mode, which is commonly seen in a greenhouse, typically requires a single-level cultivation tank having a length of more than 30 meters and an inclining arrangement with a certain degree of slope. Yet for a plant cultivation facility using an artificial light to grow plants indoors, a 20 m-30 m long span of building is rarely seen, and thus difficult to be obtained, in most regular buildings. As such a multi-level plant cultivation system is generally applied.
Currently in a conventional multi-level plant cultivation system, each cultivation tank typically contains a liquid that is deeper than the shallow cultivation mode as mentioned above (i.e. a deep cultivation mode), and as such resulting in a larger load, which in turns leads to higher requirements for the bearing capability, and for the composition material as well, of the multi-level plant cultivation system.
To accommodate these above requirements, the main frame of the multi-level hydroponic cultivation system as mentioned above is typically built with metal parts, assembled typically by welding or screw fixation. In such a multi-level hydroponic cultivation system, a cultivation tank is disposed on each level of the main frame, which typically comprises a foam material having relatively good thermal insulation, and a PE film. A plant growth-compatible lamp, which is commonly independent from the cultivation tank, is disposed on each level, and typically comprises a fluorescent lamp or a light emitting diode (LED) as the plant growth-compatible light source.
Due to limited space and varied sizes of buildings, during construction and installation of the plant cultivation facilities, all the materials and compositions need on-site customization; for example, all the metal parts required for the main frame need on-site cutting, and all the film for the cultivation tanks also need on-site cutting. Additionally, welding or screwing of metal parts is needed to build the main frame; adhesive tapes, glues, etc. are needed for arrangement of PE films; and wiring and a hanging structure is also needed for mounting the LED lamps.
As such, the whole process of assembling a conventional plant cultivation facility as described above is quite complicated. Disassembling and/or maintenance of the plant cultivation facility as described above are similarly very complicated and incurs a high labor cost. In addition, the metal frame, screws and other metal parts are prone to rust over time, and the life of PE films is short, which requires replacement every 2 years or so. Furthermore, the multi-level plant cultivation facility itself may likely exceed the load-bearing requirement of a general floor of a regular building, and a multi-level cultivation system as such is difficult to be built in buildings having multiple floors.
These issues associated with conventional plant cultivation technologies as mentioned above have greatly limited their wide application in real practice.